Straight fluorescent lamp with surface-mounted electrical conduit

ABSTRACT

The invention concerns the configuration of a fluorescent lamp, which consists only of a single, straight glass tube as gas discharge vessel, which is modified to a “compact fluorescent lamp” with integrated ballast by one-sided mounting by means of electrical connections applied to the glass tube.  
     Additional application examples are presented.

[0001] Although long, straight fluorescent lamps have the largest marketshare in lighting technology and have gained acceptance worldwide formany years, only a few significant improvements have been made in thefurther development of these lamps. These include the switch toelectronic ballasts, a certain improvement in fluorescent material and areduction in the diameter of the glass tube.

[0002] The high cost in the manufacture of lamps and light strips wasperceived as a necessary evil and attempts were made to reduce themanufacturing costs by using terribly expensive robots. This primarilyconcerns the laying of millions of kilometers of connection lines in thelamps, whose electrodes must each be connected with two wires over theentire length of the lamps.

[0003] The task of the invention is to radically reduce this expense,and not only to save costs, but also to devise additional lamp designsand applications of these energy-saving fluorescent lamps.

[0004] This objective is achieved by equipping these long, straightglass tubes, that serve as gas discharge vessels, on one end in theregion of the first electrode with all required connections forconnection to the electronic ballast and running the requiredconnections to the second electrode outside of the glass tube. Forexample, this would also be possible with wires that are inserted in alongitudinal groove, in order to protect them from damage.

[0005] It is technologically much simpler to apply conductive coatingsto the glass tube as connection lines, which are additionally coveredwith a protective layer.

[0006] The solution is simplified in that the number of requiredconnection lines is reduced. This can be achieved according to theinvention in that the second electrode is not heated, both ends of thecoiled electrode then being simply connected to each other. This methodis feasible, but, among other things, leads to a shortening of thelifetime of the lamp. It is better to use so-called “unheated, coldelectrodes”, which are equipped with a large amount of emitter paste andwere deliberately developed with other measures for an unheated, coldstart.

[0007] In order to make possible contact with the metal coatingsnonhazardous, it is recommended according to the invention that these bemade potential-free by a protective capacitor. Since transmission of thelamp current occurs with a high frequency to 100 kHz, only smallcapacitance values are required, which entail no contact hazard for alow line frequency of 50 or 60 Hz, especially if additional insulationprotects against contact.

[0008] It is expedient to equip the lamps in the region of the secondelectrode, i.e., on the “free” end, with means to mount or support thelamp.

[0009] A significant additional improvement consists of providing thehousing of the electronics with a base for insertion in a light socket.This produces a “compact” fluorescent lamp with integrated electronics,as are present in large numbers on the market in the small lamps forhousehold use with a base on one side. In these lamps, the one-sidedbase is achieved in that the gas discharge vessel, i.e., the glass tube,is either bent in a U-shape or melted together from two individual glasstubes, a method that cannot be rationally used in long glass tubes.

[0010] The subsequent figures serve for understanding of the inventiveconcept and its progressiveness. They cannot describe all the details ofthe invention, since there are numerous manufacturing variants anddesign possibilities that permit application of the invention. In thefigures:

[0011]FIG. 1 and FIG. 1a show a fluorescent lamp mounted on one sidewith integrated ballast.

[0012]FIG. 2 and FIG. 2a show a lamp with a longitudinal groove mountedon one side.

[0013]FIG. 3 and FIG. 3a show a lamp with an unheated, cold electrodemounted on one side.

[0014]FIG. 4 shows a compact fluorescent lamp with an Edison screw base.

[0015]FIG. 5 shows a compact fluorescent lamp with a separable ballast.

[0016] The following description provides practical examples of theinvention. The same functional parts are given the same referencenumbers in all figures.

[0017] The gas discharge lamp (1) depicted in FIGS. 1 and 2 is equippedwith two heated electrodes (8), which require, in principle, twoterminals. Two outer connection lines (8) are therefore schematicallyshown in FIG. 1, which supply the second electrode (6) withoutindicating how these run along gas tube (1). In the enlarged, alsoschematically depicted section of FIG. 1a, the connection lines (8) areshown as vapor-deposited or printed conductor paths, which are coveredby an insulation layer (16).

[0018] The ballast (2) is accommodated in the housing (17), having a pinbase (4), and can be plugged into a socket (3). The spring contacts (12)are on line voltage (13) and supply the lamp with the required voltage.On the other end, a glass tube (1) is protected from damage with an endcap (15). This end cap (15) can be designed in the usual shape as acombined metal-plastic part. The arrangement of a mount (11) to supportthe free end of the lamp is important. The mount (11) can be molded ontothe plastic part of the end cap (15) or the otherwise common massproduced end caps with contact pins can also be used as mount.

[0019]FIG. 2 shows two additional details. The second electrode isinitially simply shorted, in order to save outer connection (8). Theremaining single outer connection (18) is shown as a wire embedded in alongitudinal groove of glass tube (1). The enlarged schematic section ofFIG. 2 shows this.

[0020] The depicted longitudinal groove is not a special feature of thislamp, but has been provided by individual companies for many years toimprove the ignition and burning properties of the gas discharge. Thistechnology requires no special development.

[0021] The problem of the 2^(nd) electrode is solved in the example ofFIG. 3, essentially in that two unheated electrodes (7) are provided,which withstand the more severe starting conditions without difficultwhen properly dimensioned.

[0022] The outer connection (8) in this example, as shown in FIG. 3a, isdepicted as a vapor-deposited or printed conducting path, which requiresno additional contact protection if the capacitor (10) arranged inballast (2) meets the safety provisions of the corresponding regionalauthorities.

[0023] An additional effect of the applied conducting path consists ofthe fact that a reduction of ignition voltage is obtained, as has beenused already for many years by such ignition strips. This is primarilyhighly desirable at the otherwise increased ignition voltage in coldelectrodes.

[0024] The example of FIG. 4 represents an expansion in principle. Byarranging a base that can be inserted into the lamp sockets, the lampbecomes a compact fluorescent lamp with integrated ballast, a truemarket gap that can finally be filled. The shown Edison screw socket waschosen because it is well known. However, a protected-type socketsystem, for example, according to German Examined Patent Application D197 07 048 A1, is prescribed because of the present strict regulations.

[0025]FIG. 5 shows another example of how a lamp according to theinvention can be used cost effectively. The gas discharge vessel (1) isequipped with a 3-pole pin base (4), which permits mechanical andelectrical separation of the electronic ballast (2). Should the lampbecome unusable, the ballast (2), which normally has a much longerlifetime, can be reused and only the lamp part need be replaced.

[0026] The basic idea of further developing a fluorescent lamp,consisting merely of a single, straight gas discharge to a lamp mountedon one side, offers a wide variety of application possibilities, asshown in the cited examples. As an additional example, the possibilitycan merely be mentioned of using the gas discharge lamp according toFIG. 5 in a base (3), in which an electronic ballast (2) isincorporated, a solution that appears to be both cost-effective andunbeatable, in terms of space requirements and service. A lamp that isequipped with such a combination requires almost no internal wiring.

[0027] The cited examples offer many additional hints that build on theinvention and its indirect scope of protection. Any combination ofproperties shown in the examples is naturally possible. The examples inthis respect are not to be interpreted as restrictive.

1. Straight fluorescent lamp with ballast, consisting of a single,straight glass tube as gas discharge vessel, which has electrodes onboth ends and is connected to an electronic ballast to generate therequired operating voltages, characterized by the fact that allterminals of the gas discharge vessel relative to the ballast aresituated on one end of the gas discharge vessel in the region of thefirst electrode and at least one outer electrical connection to thesecond electrode on the other end of the glass tube is present on theglass tube.
 2. Straight fluorescent lamp according to claim 1,characterized by the fact that at least the second electrode is designedas an unheated electrode.
 3. Straight fluorescent lamp according to oneof the preceding claims, characterized by the fact that at least one ofthe outer connections is applied as a metal coating on the glass tube.4. Straight fluorescent lamp according to one of the preceding claims,characterized by the fact that at least one of the outer connections isembedded in a longitudinal groove of the glass tube.
 5. Straightfluorescent lamp according to one of the preceding claims, characterizedby the fact that at least one of the outer connections is separated fromthe potential of the ballast by a capacitor.
 6. Straight fluorescentlamp according to one of the preceding claims, characterized by the factthat means to mount or support the glass tube are present in the regionof the second electrode.
 7. Straight fluorescent lamp according to oneof the preceding claims, characterized by the fact that the housing ofthe electronic ballast is provided with a base for connection to a lampsocket.
 8. Straight fluorescent lamp according to one of the precedingclaims, characterized by the fact that the gas discharge vessel has aplug-in base and is connected separably to the ballast via this base.